Quote:
Originally Posted by vstech
well, which is it? 
exactly HOW good are you with a mig?  |
I know this was a chuckle, but I am going to answer it as a serious question.
Here is an example of a simple high pressure pipe weld.
Stick Welding 2 inch Pipe Cover Pass - 6g Pipe Welding Test 2" Schedule 80 - YouTube
The joint needs to be a single-Vee or a single-U...
.
As the pipe size gets smaller, the difficulty goes up.
* Heat control, burn holes.
* Collapsed tube.
* Blocked tube, penetration/slag.
* Grinding the outer diameter.
* Boring and cleaning the tube bore.
Then comes the fun.
You must use
stress relieving, and I prefer
annealing.
After welding, you can do high temp stress relieve at 1250° F, for 1-1.5 hr per inch of material thickness, 1 hour minimum, as opposed to a true anneal. Furnace cool if possible.
After welding low carbon steel (under 0.25 carbon) I usually normalize which helps "homogenize" the material.
To anneal then normalize is called "double draw", which is critical if you plan to
carburize or do other heat treating later.
Annealing range for 1018 steel is 1575° F -1650° F. Time at temp 1/2 hr for small section (13 mm or less), 1 hr for 25mm section.
Recommended furnace cooling rate of 50° F/hr over range from 1575° F to 1300° F for HB 111-149.
(from metals handbook)
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From my cost perspective:
# 3-4 hours labor.
# Weld and Annealing furnace fuel $50.00
# Building a solid and safe (small)
Annealing Furnace, $200.00 + 24 hours labor.
IMO all of this is possible for the most skilled professional or most tenacious hobbyist.
It is not cost effective.
A single mistake in any of these processes will frequently turn the (used part) work piece into scrap metal.
The failed line may have formed preliminary stress fractures on the other end, just waiting to break.
.